1. Field of the Invention
The present invention relates to video projection devices for displaying, on screens, videos having been magnified and projected by optical engines, and more particularly, relates to video projection devices with reduced thicknesses.
2. Description of the Background Art
Conventionally, in a video projection device including a screen provided in a cabinet in its front side and optical devices placed within the cabinet, in order to attain reduction of the thickness of the video projection device and reduction of its height, there have been employed a structure in which an optical engine, a first reflection optical device having a planar-shaped reflection surface for folding video light emitted from the optical engine to project it onto the screen, and a second reflection optical device having a reflection surface with a rotationally-symmetrical shape centered on an optical axis are placed on a video-light path, and they are housed within the cabinet in a compact manner.
For example, Japanese Patent Application Laid-Open No. 2011-7940 discloses a video projection device having a structure in which, on a video-light path, a top plate mirror, a non-spherical mirror and a folding mirror for folding the optical path are placed within a cabinet. Further, the device described in Japanese Patent Application Laid-Open No. 2011-7940 is structured such that an optical engine incorporating the folding mirror and the non-spherical mirror is comprehensively held by a main frame which holds a screen, which prevents distortions induced in a bottom-frame side from being transferred to the main frame which holds the optical engine, thereby preventing the occurrence of distortions in images on the screen.